The patent doesn't claim to apply to domains - it claims to apply to URLs of the form name.subdomain.domain. The mere fact that this isn't correct syntax for URLs didn't prevent them from getting the patent, but it should make enforcing it on people who are using *domain names* of that form much harder, because URLs and domain names are much different semantic concepts. Of course the whole thing's a bogus crock anyway, but if they try to take it to court, and try to contend that it also covers domain name, there's more than a decade of publicly documented prior-art use of that syntax in BIND.